explain
AD7843 is a 12 bit serial analog ADC with a synchronous serial interface and a low resistance switch for driving touch screens. This component operates from a power supply ranging from 2.2 V to 5.25 V, with a throughput greater than 125 kSPS.
The external reference applied to AD7843 can vary from 1V to+VCC, while the analog input range is from 0V to VREF. The device includes a shutdown mode that reduces current consumption to less than 1 µ A.
AD7843 uses onboard switches. Combined with low power and high-speed operation, this device makes it an ideal choice for battery powered systems, such as personal digital assistants with resistive touch screens and other portable devices. This part has a 16 lead 0.15-inch quarter size contour package (QSOP) and a 16 lead thin shrink small contour package (TSSOP).
FEATURES
4-wire touch screen interface
Specified throughput rate of 125 kSPS
Low power consumption:
1.37 mW max at 125 kSPS with VCC = 3.6 V
Single supply, VCC of 2.2 V to 5.25 V
Ratiometric conversion
High speed serial interface
Programmable 8-bit or 12-bit resolution
2 auxiliary analog inputs
Shutdown mode: 1 µA max
16-lead QSOP and TSSOP packages
APPLICATIONS
Personal digital assistants
Smart hand-held devices
Touch screen monitors
Point-of-sales terminals
Pagers